Key:  Order Nuculida (Palaeotaxodonta)

Phylum Mollusca
 Class Bivalvia
  Subclass Protobranchia

Taken primarily from  Kozloff, 1987, 1996 p. 266 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)
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1a  Ligament external; interior of valves porcellanous, not pearly; with a pallial sinus (animal with siphons) 2
1b Ligament internal; interior of valves pearly, especially when fresh; without a pallial sinus Family Nuculidae
2a With a chondrophore on the lower part of the hinge plate 3
2b Without a chondrophore 4
3a Shell closing tightly, pallial sinus shallow Family Nuculanidae
3b Shell gaping posteriorly; pallial sinus deep Family Yoldiidae
4a Series of hinge teeth posterior to the umbo nearly twice as long as the series anterior to the umbo; posterior ends of valves rounded Family Malletiidae
4b Series of hinge teeth posterior to the umbo not much longer than the series anterior to the umbo; posterior ends of valves somewhat pointed due to way the the curved ventral margin meets the nearly straight dorsal margin Family Tindariidae



Taxonomic Levels Represented in This Key:

  Family Yoldiidae



Page created by Dave Cowles, 2006
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